The Head-Direct EF1 amplifier represents an amazing price performance ratio even though it is almost twice as expensive as some of the other amplifiers I have owned or tested over the last six months. Compared to some of the other amps this is a serious piece of kit with a substantial price tag to boot. At $399 this amp cannot be considered a bargain for the average listener, but for the few that crave amazing sound quality this amp is definitely worthy of your consideration and will probably yield a very good price performance ratio compared to the rest of the sub $400 market.
One of the great feats of this amp is that it can drive pretty much every headphone you can throw at it in a very convincing way. I have yet to find a headphone in my inventory where the Head-Direct EF1 does not improve their performance. I found this amp to mate well with both my Sennheiser HD 580s and AKG K701s. The amp is very versatile which in my book is a major plus. The fact that it has the power and refinement to drive a large variety of cans is extremely neat.